US5521231A - Process for producing thermoplastic copolymer powder - Google Patents

Process for producing thermoplastic copolymer powder Download PDF

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US5521231A
US5521231A US08/381,888 US38188895A US5521231A US 5521231 A US5521231 A US 5521231A US 38188895 A US38188895 A US 38188895A US 5521231 A US5521231 A US 5521231A
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polymer
weight
thermoplastic polymer
coagulation
parts
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Fumio Suzuki
Haruki Sato
Masaki Sugihara
Wataru Hadano
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Mitsubishi Chemical Corp
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Mitsubishi Rayon Co Ltd
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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F291/00—Macromolecular compounds obtained by polymerising monomers on to macromolecular compounds according to more than one of the groups C08F251/00 - C08F289/00
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
    • C08F6/00—Post-polymerisation treatments
    • C08F6/14—Treatment of polymer emulsions
    • C08F6/22—Coagulation
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J3/00—Processes of treating or compounding macromolecular substances
    • C08J3/12—Powdering or granulating
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J3/00—Processes of treating or compounding macromolecular substances
    • C08J3/12—Powdering or granulating
    • C08J3/16—Powdering or granulating by coagulating dispersions
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2321/00—Characterised by the use of unspecified rubbers
    • C08J2321/02—Latex

Definitions

  • the present invention relates to a process for producing a thermoplastic copolymer powder with high bulk specific gravity.
  • thermoplastic resin powder has high bulk specific gravity in view of efficient utilization of the storage space of the powder as a product and incidental reduction of its transportation cost.
  • thermoplastic resin powder many studies have been made on the method for elevating bulk specific gravity of thermoplastic resin powder. For example, many researches have been conducted on means for improving powder properties of the powdery or granular polymers recovered from graft copolymer latices containing an elastomeric backbone polymer in a high ratio.
  • U.S. Pat. No. 4,897,462 discloses a method for carrying out slow coagulation of a polymer latex in the presence of a coagulant of a specific concentration.
  • U.S. Pat. No. 4,275,178 discloses a method for improving the powder properties such as bulk specific gravity and blocking resistance of the produced coagulated slurries or dry powders by adding a hard polymer thereto.
  • the former method characterized by the slow coagulation in the presence of a coagulant of a specific concentration is capable of providing a spherical powder with a narrow particle size distribution, but it has disadvantages in that because of high water content of the powder after dehydration, when a heat treatment is carried out at a high temperature during solidification for obtaining the solid particles, the fine individual particles in the coagulated particles may be fused together without compacted sufficiently, making it unable to obtain the coagulated particles with high density and, consequently there can not be obtained the particles of high bulk specific gravity.
  • the latter method characterized by the addition of a hard polymer for improving the powder properties is designed to elevate bulk specific gravity of the powder by densifying the filled structure of the coagulated particle agglomerates by such means as cohesion of the coagulated particles, but this method has the problem that the effect of improving the density of the coagulated particles themselves can not be expected and a powder with a well satisfactory bulk specific gravity can not be obtained.
  • the present inventors have pursued further studies with a view to solving the above problems and, as a result, found that a polymer powder with a high bulk specific gravity comprising the compacted particles can be obtained by adding a specific polymer and/or an inorganic compound to a coagulation slurry or polymer powder obtained from a thermoplastic polymer latex and compressing and comminuting the resulting polymer powder.
  • the present invention has been attained on the basis of this finding.
  • the present invention provides a process for producing a thermoplastic polymer powder which comprises adding a polymer (B) and/or an inorganic compound (C) to a coagulation slurry of a thermoplastic polymer (A) obtained by emulsion polymerization and having a glass transition temperature Tg defined by the following equation (1) or to a polymer powder obtained by drying said coagulation slurry, said polymer (B) and/or inorganic compound (C) being added in an amount of 0.1-10 parts by weight to 100 parts by weight of said thermoplastic polymer (A), compressing the thermoplastic polymer (A) at a temperature in the range of (Tg-30) to (Tg+50)° C. and then comminuting the mixture:
  • FIG. 1 is a diagrammatic illustration of the apparatus used in the production process of the present invention.
  • the method of emulsion polymerization may be one commonly practiced in the art.
  • the initiator and other polymerization assistants are not subject to any specific restrictions, and those commonly used in the art may be employed.
  • the monomers usable for forming the thermoplastic polymer (A) in the present invention there can be mentioned various types of copolymerizable monomers, for example, dienes such as butadiene, isopropylene and chloropropylene; alkyl acrylates such as butyl acrylate and octyl acrylate; alkyl methacrylates such as methyl methacrylate and ethyl methacrylate; vinyl cyanides such as acrylonitrile and methacrylonitrile; aromatic vinyl compounds such as styrene and ⁇ -methylstyrene; and vinyl halides such as vinyl chloride and vinyl bromide.
  • dienes such as butadiene, isopropylene and chloropropylene
  • alkyl acrylates such as butyl acrylate and octyl acrylate
  • alkyl methacrylates such as methyl methacrylate and ethyl methacrylate
  • vinyl cyanides such as acrylon
  • thermoplastic polymer (A) is a graft copolymer obtained by emulsion polymerizing a hard polymer-forming monomer with an elastomeric backbone polymer, especially said type of graft copolymer in which the content of the elastomeric backbone polymer is 60% by weight or more.
  • elastomeric backbone polymers constituting said graft copolymers
  • the polymers of dienes such as butadiene, isoprene and chloroprene
  • polymers of acrylic esters in which the alkyl group has 4-10 carbon atoms such as butyl acrylate and octyl acrylate
  • copolymers of dimethylsiloxane polymers and monomers coplymerizable therewith there can be mentioned the polymers of dienes such as butadiene, isoprene and chloroprene
  • acrylic esters in which the alkyl group has 4-10 carbon atoms such as butyl acrylate and octyl acrylate
  • copolymers of dimethylsiloxane polymers and monomers coplymerizable therewith such as butadiene, isoprene and chloroprene
  • aromatic vinyl compounds such as styrene and ⁇ -methylstyrene
  • alkyl methacrylates such as methyl methacrylate and ethyl methacrylate
  • alkyl acrylates in which the carbon number of alkyl is 1-3 such as methyl acrylate and ethyl acrylate
  • vinyl cyanides such as acrylonitrile and methacrylonitrile.
  • the monomers forming a hard polymer the following can be mentioned: aromatic vinyl compounds such as styrene and ⁇ -methylstyrene; alkyl methacrylates such as methyl methacrylate, ethyl methacrylate and butyl methacrylate; vinyl cyanides such as acrylonitrile and methacrylonitrile; and vinyl halides such as vinyl chloride and vinyl bromide.
  • aromatic vinyl compounds such as styrene and ⁇ -methylstyrene
  • alkyl methacrylates such as methyl methacrylate, ethyl methacrylate and butyl methacrylate
  • vinyl cyanides such as acrylonitrile and methacrylonitrile
  • vinyl halides such as vinyl chloride and vinyl bromide.
  • thermoplastic polymer (A) in the present invention is one having a glass transition temperature Tg defined by the above-shown equation (1).
  • thermoplastic polymer (A) When a coagulant is added to a latex of thermoplastic polymer (A), the emulsified state of the latex gives way and the polymer particles which have been dispersed as emulsion in the latex are aggregated to form the particle agglomerates (which are hereinafter referred to as coagulated particles), and these coagulated particles are dispersed in a dispersing medium such as water to form a coagulation slurry.
  • a dispersing medium such as water
  • thermoplastic polymer (A) For further densifying the thus formed quality-improved coagulated particles, they are usually subjected to a heat treatment comprising heating them to a temperature above Tg of the thermoplastic polymer (A).
  • This treatment is generally called solidification.
  • the solidification temperature depends on Tg of the thermoplastic polymer (A), but the treatment is usually carried out at a temperature of 60°-120° C.
  • the resulting slurry is dehydrated and dried, recovering the thermoplastic polymer (A) as a powder.
  • polymer (B) and/or inorganic compound (C) are added to a slurry after coagulation, but in the present invention, said addition and mixing can be conducted at any stage as far as it is posterior to coagulation.
  • Solidification of the latex of thermoplastic polymer (A) can be effected by using any suitable method such as a method using a stirrer, a method in which the latex is injected into the coagulant from a nozzle, and a method in which the latex is atomized into a coagulant atmosphere.
  • a sulfuric ester type and/or sulfonic acid type anionic surfactant to exist in said polymer latex.
  • the amount of this surfactant is preferably 0.05-0.5 parts by weight to 100 parts by weight of thermoplastic polymer (A).
  • the amount of said surfactant added is preferably 0.05-0.15 parts by weight.
  • sulfuric ester type anionic surfactants there can be cited, for example, higher alcohol sulfurates and polyoxyethylene alkylsulfates.
  • sulfonic acid type anionic surfactants there can be mentioned, for example, alkyl sulfonates, alkylbenzene sulfonates, alkyl sulfosuccinates and alkyldiphenyl ether sulfonates.
  • the surfactant may be added before, during or after polymerization.
  • the emulsified state-retaining action of the surfactant undesirably becomes too weak to resist the emulsified state breaking action of the coagulant acid, making it difficult to control the state of precipitation of the coagulated particles in a stabilized way and to obtain a powdery polymer with a narrow particle size distribution.
  • the amount of the surfactant added exceeds 0.5 parts by weight, the emulsified state retaining action of the surfactant becomes too strong, making it unable to induce coagulation without using a large amount of acid.
  • acids for example, inorganic acids such as hydrochloric acid,sulfuric acid, phosphoric acid, etc., and organic acids such as formic acid, acetic acid, etc.
  • inorganic acids such as hydrochloric acid,sulfuric acid, phosphoric acid, etc.
  • organic acids such as formic acid, acetic acid, etc.
  • the coagulated slurry was filtered by Toyo filter paper No. 131 (JIS P3801, Class 3) and the polymer concentration in the filtrate was measured to determine the amount of the uncoagulated polymer, from which the amount of the coagulated polymer was calculated.
  • the amount of the coagulated polymer is less than 40% by weight, a substantial portion of the copolymer latex is undesirably coagulated under a strong emulsified state disrupting action at the time of completion of coagulation, making it difficult to obtain a powdery polymer with a narrow particle size distribution.
  • the amount of the coagulated polymer is greater than 80% by weight, the emulsified state disrupting action is too strong and it is difficult to obtain a powdery polymer with a narrow particle size distribution.
  • the acid used in the first stage coagulation is preferably added to the latex in such a way that the pH of the slurry during coagulation will meet the condition of the following formula (2): ##EQU1## (wherein X is parts by weight of the sulfuric ester type and sulfonic acid type anionic surfactants per 100 parts by weight of thermoplastic polymer (A)).
  • the emulsified state retaining action of the surfactant becomes too strong vis-a-vis the emulsified state disrupting action of the acid, resulting in inhibiting occurrence of coagulation or requiring long time until coagulation occurs.
  • the same acids as used in the first stage coagulation mentioned above and the salts thereof for example, inorganic salts such as aluminium sulfate, magnesium sulfate, sodium chloride, calcium chloride, sodium sulfate, magnesium chloride, etc., and organic salts such as sodium acetate, calcium acetate, etc., can be cited. These acids and salts may be used either singly or as a mixture.
  • the pH of the slurry after perfect precipitation of the coagulated particles be adjusted to 2.0 or above.
  • the pH of the coagulation slurry is less than 2.0, the obtained polymer powder proves to be undesirably poor in thermal stability.
  • pH is preferably adjusted to be 2-4 with an alkali such as sodium hydroxide.
  • the polymer (B) used in the present invention is purposed to provide a powder quality improving action for enhancing the efficiency of the comminution step by adding it to thermoplastic polymer (A).
  • Polymer (B) is preferably a resin having a glass transition temperature which is more than 50° C. higher than Tg of said polymer (A).
  • thermoplastic polymer (A) and polymer (B) When the difference in glass transition temperature between thermoplastic polymer (A) and polymer (B) is less than 50° C., the powder reforming effect of polymer (B) undesirably lowers.
  • the glass transition temperature of polymer (B) used in the present invention can be represented by the above-shown equation (1) where thermoplastic polymer (A) is replaced with polymer (B).
  • the monomers forming polymer (B) there can be used the same monomers as those forming thermoplastic polymer (A).
  • the amount of polymer (B) and/or inorganic compound (C) added is 0.1-10 parts by weight, preferably 0.5-5 parts by weight, to 100 parts by weight of thermoplastic polymer (A).
  • the amount is less than 0.1 part by weight, the improvement of polymer (A) particle surface is insufficient and comminution of the powder after compaction becomes hard to perform in a desired way, making it unable to obtain the objective powder.
  • said amount exceeds 10 parts by weight, an undesirable change of the normal properties of thermoplastic polymer (A) may be caused.
  • the average particle size of polymer (B) and inorganic compound (C) is preferably not greater than 10 ⁇ m. When it exceeds 10 ⁇ m, it undesirably becomes necessary to add a large amount of polymer (B) and/or inorganic compound (C) for improving the polymer (A) particle surface.
  • the particle size of polymer (B) and inorganic compound (C) is as small as possible, preferably less than 0.5 ⁇ m.
  • Polymer (B) and/or inorganic compound (C) may be added in the state of latex, solidified slurry or dry powder.
  • the time of addition may be after coagulation, during the heat treatment, after the dehydration or after the drying of thermoplastic polymer (A), but in the case of a highly coherent polymer, it is preferably added to the coagulation slurry before solidified.
  • thermoplastic polymer (A) is a graft copolymer obtained by emulsion polymerizing a hard polymer-forming monomer with an elastomeric backbone polymer and having an elastomeric backbone polymer content of 60% by weight or more
  • the powder reforming polymer (B) is preferably one which has a glass transition temperature higher than 25° C., preferably higher than 60° C.
  • polymer (B) is preferably one produced from a monomer mixture containing at least 80% by weight of one or more of monomers selected from the group consisting of methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, styrene and ⁇ -methylstyrene.
  • the rest of the monomer mixture may comprise other copolymerizable ethylenic unsaturated monomer(s), for example, soft polymer-forming monomers such as acrylates in which the alkyl group has 1-4 carbon atoms.
  • Inorganic compound (C) used in the present invention is designed to produce the same effect as polymer (B).
  • oxides, chlorides, hydroxides, carbonates and sulfates of one or more of elements selected from the group consisting of Si, Mg, Al, Ca, Ba, Zn and Ti either singly or as a mixture thereof.
  • Typical examples of such compounds are SiO 2 , MgO, Mg(OH) 2 , MgCO 3 , Al 2 O 3 , Al(OH) 3 , Al 2 (CO 3 ) 3 , CaO, CaCO 3 , TiO 2 , talc, clay, diatomaceous earth and calcium metasilicate.
  • These inorganic compounds are preferably ones whose solubility in water at 25° C. is 0.5 g/100 ml or below.
  • the coagulated particles obtained in the present invention are subjected to a solidification treatment, then dehydrated and dried.
  • the particles are usually solidified at a temperature in a range of 60°-120° C.
  • this solidification treatment is carried out at a high temperature for a long time, the water content of the wet powder after dehydration lowers, making it possible to reduce the heat energy required in the drying step.
  • thermoplastic polymer (A) is discussed. Compaction is conducted for reducing the voids existing in the inside of the coagulated particles of the recovered powder of thermoplastic polymer (A).
  • the powder of thermoplastic polymer (A) is formed into blocks. Since the coagulated particle surface has been reformed by polymer (B) and/or inorganic compound (C), said blocks can be easily comminuted to the original state of individual coagulated particles. Consequently, the voids in the inside of the coagulated particles are reduced and the inside of the particle is brought into a densified state.
  • the available methods for compaction include, but are not limited to, tableting and briquetting by use of a compaction granulator or extrusion granulator.
  • thermoplastic polymer (A) When the powder of thermoplastic polymer (A) is compacted without reforming of the coagulated particles, it is impossible to break down the blocks to reduce them into the original state of individual coagulated particles, making it unable to realize an increase of bulk specific gravity which is the object of the present invention.
  • thermoplastic polymer (A) is carried out at a temperature in a range of (Tg-30) to (Tg+50)° C. (wherein Tg is glass transition temperature of thermoplastic polymer (A)).
  • Tg glass transition temperature of thermoplastic polymer (A)
  • thermoplastic polymer (A) is especially useful as thermoplastic polymer (A) in the process of this invention as such a copolymer is effective for enhancing bulk specific gravity by compaction at around normal temperature.
  • the pressure used for compaction is 100-1,000 kg/cm 2 , preferably 200-700 kg/cm 2 , in terms of areal pressure, and 100-1,000 kg/cm, preferably 100-700 kg/cm, in terms of linear pressure.
  • the pressure applied is below the lower limit defined above, the densifying effect is insufficient and a satisfactory bulk specific gravity cannot be obtained.
  • the pressure exceeds the above-defined upper limit or when compaction is carried out without surface reforming of the coagulated particles it is impossible to break up the blocks to return them to the original state of individual coagulated particles, making it unable to attain enhancement of bulk specific gravity purported in the present invention.
  • the compaction step may be carried out either after dehydration of thermoplastic polymer (A) or after drying thereof.
  • Various means for example, crushers such as hammer crusher, milling machines such as hammer mill or pin mill, and pulverizers such as jet mill can be used for breaking up the compacted blocks. These breaking means are properly selected according to the hardness of the blocks. They may be used in combination.
  • a typical example of apparatus used in carrying out the second stage coagulation in the process of this invention is here explained with reference to FIG. 1.
  • a copolymer (A) latex is supplied into first tank 5 from metering pump 1 while an acid is also supplied into said tank from metering pump 2.
  • First stage coagulation is accomplished in said first tank 5 and the coagulation slurry is overflown into second tank 6.
  • the acid for enhancing the polymer recovery is supplied to second tank 6 from metering pump 3.
  • Coagulation is completed in said second tank 6.
  • To third tank 7 is supplied an alkali serving as a slurry pH adjustor from metering pump 4.
  • the slurry is heat treated in fourth tank 8 and then further subjected to water washing, dehydration, drying, compaction and comminution, although not shown in the drawing, to obtain a desired polymer powder.
  • thermoplastic polymer (A-1) Preparation of thermoplastic polymer (A-1)
  • the feedstock of the above composition was supplied to a pressure autoclave and reacted with stirring at 50° C. for 48 hours to prepare a rubber latex (polymerization rate: 98%).
  • One part of sodium chloride was added to 70 parts (as solids) of said rubber latex, followed by further addition of a mixed monomer consisting of 13 parts of methyl methacrylate, 2 parts of ethyl acrylate and 0.045 part of cumene hydroperoxide and 0.06 part of formaldehyde sodium sulfoxylate, and the mixture was subjected to first stage graft polymerization at 70° C. for 2 hours.
  • thermoplastic polymer (A-1) (solids concentration: 36%; average particle size: 0.115 ⁇ m).
  • a mixture consisting of 280 parts of deionized water, 1 part of sodium dioctylsulfosuccinate, 0.2 part of ammonium persulfate, 85 parts of methyl methacrylate, 15 parts of butylacrylate and 0.02 part of n-octylmercaptan was supplied to a reactor equipped with a stirrer and a reflux condenser. After replacing the inside atmosphere of the reactor with nitrogen, the reactor was heated to 65° C. with stirring and the mixture therein was polymerized by heating with stirring for 2 hours to obtain a polymer (B-1) (solids: 27.8%; average particle size: 0.13 ⁇ m).
  • thermoplastic polymer (A-1) latex Two hundreds grams of the thermoplastic polymer (A-1) latex was coagulated by using 600 g of 0.23% dilute sulfuric acid in a 2-litre vessel provided with a 6-vane fan turbine type stirrer. To the resulting slurry was added the polymer B-1 having a glass transition temperature 50° C. higher than that of A1, in the state of latex. Thereafter, the slurry was heated to the solidification temperature shown in Table 1, then dehydrated and dried to obtain a pulverulent body. This pulverulent body was compacted at the temperature and under the pressure shown in Table 1 and then comminuted to obtain a powder. Bulk specific gravity of the powder was measured according to JIS K-6721. The evaluation results are shown in Table 1.
  • thermoplastic polymer (A-2) solids concentration: 33%; average particle size: 0.137 ⁇ m.
  • A-2 thermoplastic polymer
  • B-2 hydrophobic silica
  • Example 2 The procedure of Example 2 was followed except that compaction was carried out at the temperature shown in Table 1 to obtain a powder.
  • the evaluation results are shown in Table 1.
  • thermoplastic polymer (A-3) was used in place of the polymer (B-1) latex used in Example 1, and 200 g of this polymer (A-3) latex was coagulated by using 0.27% dilute sulfuric acid. To the resulting slurry was added hydrophobic silica (B-2). Thereafter, the slurry was heated to the solidification temperature shown in Table 1, then dehydrated and dried to obtain a pulverulent body. This pulverulent body was compacted at the temperature and under the pressure shown in Table 1 and then comminuted to obtain a powder. The evaluation results are shown in Table 1.
  • graft copolymer latex Fifteen parts by weight of styrene, 13.2 parts by weight of methyl methacrylate and 1.8 parts by weight of ethyl acrylate were graft polymerized onto 70 parts by weight of styrene-butadiene elastomeric backbone polymer to obtain a graft copolymer latex (solids: 36% by weight).
  • the average particle size of the obtained latex was 0.1 ⁇ m, its pH was 8.0, and the types and amounts of the surfactants existing in the latex were as shown in Table 2.
  • the above latex was coagulated by using the apparatus shown in FIG. 1.
  • said latex and the acid of the type shown in Table 2 were supplied to a first tank so that the pH of the mixture and the amount (%) of the coagulated polymer would have the values shown in Table 2.
  • the acid of the type shown in Table 2 was supplied to a second tank so that the pH of the mixture would have the value shown in Table 2.
  • an alkali of the type shown in Table 2 was supplied to a third tank so that the pH of the mixture would have the value shown in Table 2.
  • the temperature of each tank was controlled to have the value shown in Table 2.
  • the slurry discharged out from a fourth tank was washed with water, dehydrated and dried, and then 0.5% by weight of hydrophobic silica (produced by Nippon Aerosil Co., Ltd.; Lot No. R972; average particle size: 0.014 ⁇ m) was dry blended to obtain a dry powder.
  • hydrophobic silica produced by Nippon Aerosil Co., Ltd.; Lot No. R972; average particle size: 0.014 ⁇ m
  • the obtained dry powder was compacted by a 50-mm diameter tableting machine under a pressure of 300 kg/cm 2 to form blocks. These blocks were comminuted by using a screen mill to obtain a polymer powder.
  • D 75 is particle diameter ( ⁇ m) at the 75% point of the cumulative weight distribution curve
  • D 25 is particle diameter ( ⁇ m) at the 25% point of the cumulative weight distribution curve
  • the dry powder was put into a gear oven kept at 120° C. and the change of thermal coloration with time was visually evaluated by rating the state of coloration according to the following 3-grade criterion:
  • Polymer powders were obtained in the same way as in Example 4 except that the type of the surfactant existing in the latex, pH of the first tank and the amount of the coagulated polymer were changed as shown in Table 2. The evaluation results are shown in Table 2.
  • a polymer powder was obtained in the same way as in Example 4 except that the amount of the surfactant existing in the latex, pH of the first tank, the amount of the coagulated polymer and pH of the second tank were changed as shown in Table 2, and that no alkali was added to the third tank and its pH was changed as shown in Table 2.
  • the evaluation results are shown in Table 2.
  • a polymer powder was obtained in the same way as in Example 4 except that the type and amount of the surfactant existing in the latex, pH of the first tank, the amount of the coagulated polymer and pH of the second tank were changed as shown in Table 2, and that no alkali was added to the third tank and its pH was changed as shown in Table 2.
  • the evaluation results are shown in Table 2.
  • Polymer powders were obtained in the same way as in Example 8 except that the heat treatment temperature in the fourth tank was changed as shown in Table 3. The evaluation results are shown in Table 3.
  • graft copolymer latex solids: 36% by weight.
  • the average particle size of the obtained latex was 0.1 ⁇ m, its pH was 8.0 and the types and amounts of the surfactants existing in the latex were as shown in Table 4.
  • a hard non-elastomeric polymer latex obtained by emulsion polymerizing 85 parts by weight of methyl methacrylate and 15 parts by weight of butyl acrylate was added in an amount of 2 parts by weight (calculated as solids) to 100 parts by weight of the graft copolymer.
  • the temperatures of the respective tanks were controlled to have the values shown in Table 4.
  • the slurry discharged out of the fourth tank was washed with water, dehydrated and dried to obtain a dry powder.
  • the obtained dry powder was compacted to form blocks by using a roller compactor (roll diameter: 10 inches; roll width: 4 inches).
  • the obtained blocks were comminuted by using a Fitzmill mfd. by Hosokawa Micron Co., Ltd. to obtain a polymer powder.
  • the evaluation results are shown in Table 4.
  • a polymer powder was obtained in the same way as in Example 13 except that the types and amounts of the surfactants existing in the latex, pH of the first tank, the amount of the coagulated polymer and pH of the second tank were changed as shown in Table 4, and that no alkali was added to the third tank and its pH was changed as shown in Table 4.
  • the evaluation results are shown in Table 4.
  • Polymer powders were obtained in the same way as in Example 14 except that the heat treatment temperature in the fourth tank was changed as shown in Table 4. The evaluation results are shown in Table 4.
  • a polymer powder was obtained in the same way as in Example 7 except that pH of the first tank was changed as shown in Table 5, and that no acid was added to the second tank since coagulation had been completed in the first tank.
  • the evaluation results are shown in Table 5.
  • a polymer powder was obtained in the same way as in Example 7 except that pH of the first tank and the amount of the coagulated polymer were changed as shown in Table 5. The evaluation results are shown in Table 5.
  • Polymer powders were obtained in the same way as in Example 8 except that pH of the second and third tanks was changed as shown in Table 5. The evaluation results are shown in Table 5.
  • Polymer powders were obtained in the same way as in Example 7 except that the compaction pressure of the tableting machine was changed as shown in Table 6. The evaluation results are shown in Table 6. The blocks obtained in Comparative Example 3 were so solid that they could hardly be milled.
  • Polymer powders were obtained in the same way as in Example 14 except that the roll pressure of the roller compactor was changed as shown in Table 6. The evaluation results are shown in Table 6. The blocks obtained in Comparative Example 5 were so solid that they could hardly be milled.
  • thermoplastic resins it is possible to remarkably elevate bulk specific gravity of thermoplastic resins as compared with the case using the methods known in the art, and consequently, improvement of powder properties such as blocking resistance, fluidity, etc., can be expected. Also, efficient utilization of the storage space and incidental reduction of transportation cost can be attained.

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US08/381,888 1992-08-31 1993-08-31 Process for producing thermoplastic copolymer powder Expired - Lifetime US5521231A (en)

Applications Claiming Priority (5)

Application Number Priority Date Filing Date Title
JP23239192 1992-08-31
JP4-232391 1992-08-31
JP07565593A JP3163195B2 (ja) 1993-04-01 1993-04-01 粉粒状重合体の製造方法
JP5-075655 1993-04-01
PCT/JP1993/001221 WO1994005722A1 (fr) 1992-08-31 1993-08-31 Procede de production d'un copolymere thermoplastique pulverulent

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US6683123B1 (en) * 2000-09-12 2004-01-27 Bayer Polymers Llc Process for making a thermoplastic molding composition
US20040152821A1 (en) * 2001-06-11 2004-08-05 Kazunori Saegusa Polymer composition
US20070100103A1 (en) * 2005-10-13 2007-05-03 Lg Chem, Ltd. Composition of acryl-silicone complex, preparing method and use thereof
US20070219294A1 (en) * 2004-03-08 2007-09-20 Kaneka Corporation Method for manufacturing coagulated particles from latex prepared by emulsion polymerization
US11339237B2 (en) * 2018-12-21 2022-05-24 Lg Chem, Ltd. Method of preparing thermoplastic resin, thermoplastic resin prepared therfrom and thermoplastic resin composition comprising the same

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US20070100103A1 (en) * 2005-10-13 2007-05-03 Lg Chem, Ltd. Composition of acryl-silicone complex, preparing method and use thereof
US7812115B2 (en) * 2005-10-13 2010-10-12 Lg Chem, Ltd. Method for preparing high molecule latex resin powder
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US11339237B2 (en) * 2018-12-21 2022-05-24 Lg Chem, Ltd. Method of preparing thermoplastic resin, thermoplastic resin prepared therfrom and thermoplastic resin composition comprising the same

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